Birth of Metric System and First Kilogram

BIRTH OF METRIC SYSTEM AND FIRST KILOGRAM
After French Revolution, metric system was born. In 1790, 16.Louis has established a committee that consists of leading scientists and asked them to generate a new measurement weighing system. The committee has finalized its work on May 19, 1791. Recommended system wasbased on unit length. Unit length was described as one in ten million of the distance between the pole and equator and designated in meters. This weight is defined as the weight of a unit of water volume, which is calculated with this unit of length at freezing point. Louis enacted the work of committee on March 26, 1791. The committee came together for the second time in 1799.The mass standard was agreed to be defined as the weight of one cubic decimeter of water at 4 °C. This was called as kilogram. Therefore, one gram has the weight of one cubic centimeter of water. Brass weights that equal to new standard mass were manufactured. Lately, platinum mass was manufactured and calibrated so as to be equivalent to this weight. This weight was begun to be known as kilogram des archives and become the standard weight of many European countries. In 1870 and 1872, French government called to discuss metric standard and the third meeting was held. In this meeting in which eighteen countries has attended, the protection and the verification authority for metric standard was given to Committee International des Poids et Mesures (International Committee for Weights and Measures) and Bureau International des Poids et Mesures (International Bureau for Weights and Measures).As a result of this meeting, it was decided to manufacture the new kilogram from 90% platinum and 10% iridium. George Matthey of Johnson (Matthey & Co) has manufactured three cylindrical parts at above proportions and submitted to metallurgist Claire Deville. These three parts alloy were calibrated and compared with kilogram des archives. Then, one of these parts was accepted as the international prototype for kilogram and designated as K. In 1882, 40 pieces of a kilogram was ordered from Matthey & Co. These parts were manufactured in 1884 and distributed to 20 countries after calibration. This is the brief history of kilogram. The laboratories in National Metrology Institude (UME), which have been accredited with institute laboratories in different countries, operate in our country.